The object is to elucidate the mechanism of enzyme catalyzed reactions and related phenomena such as ligand binding by hemoglobin, and protein-protein interactions, by making observations on the chemical and physical properties of appropriate systems, often of a kinetic character. The observations will be compared with suitable model systems and correlated with structural and chemical information available to build up a descriptive scheme best approximating the experiment. BIBLIOGRAPHIC REFERENCES: Edelstein, S. J., and Gibson, Q.H., The Effect of Functional Differences in the alpha and beta chains on the cooperativity of the oxidation-reduction reactions of hemoglobin, J.B.C. 250, 961 (1975). Hensley, P., Edelstein, S.J., Wharton, D., and Gibson, Q.H., Conformation and Spin State in Methemoglobin, J.B.C. 250, 952 (1975).